T cell receptor (TCR) diversity is generated by rearrangement of the variable, joining, and diversity gene segments. The TCR then associates with CD3 to complete the TCR complex. γδ T cells (gamma delta T cells) are a small subset of T cells that express a unique TCR. While most T cell express a TCR composed of α and β glycoprotein chains, γδ T cells display one γ chain and one δ chain. γδ T cells are less common compared to αβ T cells but are abundant in the gut mucosa. They are also found in the thymus, peripheral lymphoid tissue, and peritoneum. Unlike αβ T cells, γδ T cells do not require antigen processing in order to recognize certain bacterial, lipid, and tumor antigens bound to MHC Class IB.

While the precise role of γδ T cells is unclear, they are known to contribute to both the innate and adaptive arms of the immune system. The rearrangement of TCR genes produces junctional diversity, allowing them to develop a memory phenotype. On the other hand, their TCR can be used as a pattern recognition receptor, responding to microbial stimulation within hours. Recent work has shown γδ T cells are capable of phagocytosis and antigen presentation.

Nomenclature

Several TCR γ and δ chains were discovered and various nomenclature systems have been used. The early nomenclature designated genes by their order of discovery, while subsequent systems began to group genes based on homology and superfamily structure. As a result, several naming systems exist, resulting in confusion regarding equivalent names for different systems. In order to consolidate the various nomenclature systems, we have created charts for corresponding names across some of the most popular naming methods.